Gas turbine engines typically comprise a compressor, at least one combustor, and a turbine. The pressure of air passing through the compressor is raised through each stage of the compressor and is then directed towards the combustion system. Gas turbine combustion systems mix fuel with the compressed air and ignite this mixture to create hot combustion gases. The hot combustion gases are then directed towards a turbine, which produces work, typically for thrust, or shaft power if the engine shaft is connected to an electrical generator.
The turbine engine is comprised of numerous individual components that are fixed together in order to provide the path through which air and combustion gases pass while undergoing the process of generating the thrust or shaft power previously mentioned. It is imperative that all gaps between these individual components be controlled in order to minimize losses in compressor, combustion, or turbine efficiency due to undesirable leakages. Due to various thermal and mechanical loads on these individual components, often times the sealing region between mating components moves or twists. Therefore, it is imperative that any seal between mating components be compliant to such movement. While various fastening and sealing means are employed to control these leakages, one common means, especially in the turbine section, is the use of individual metallic seals.
Most common metallic seal designs have included individual strips of metal and a metallic cloth seal. Examples of these types of prior art seals are shown in FIGS. 1-3. Referring now to FIGS. 1 and 2, a metallic cloth seal in accordance with U.S. Pat. No. 5,934,687 is shown and hereby incorporated for reference. Metallic cloth seals have become common due to their sealing, wear resistance features, and ease of assembly with the turbine engine. As an example, seal 110 includes a center metal sheet 130 surrounded by cloth layer assemblages 132 and 134. Cloth layers 132 and 134 are attached to metal sheet 130 by a plurality of spot welds 138, which are located towards the outer edges of cloth layers 132 and 134. While this seal design has shown improved resistance to wear, the seal has minimal flexibility, due especially to the locations of spot welds 138. In operation, seal 110 must move and bend as required in order to maintain a seal between mating components. This seal movement imparts a high bending stress on spot welds 138 that has been known to cause the the weld to crack and the cloth layer 132 and 134 to separate from center metal sheet 130.
An alternate prior art gas turbine engine seal is shown in FIG. 3 and consists essentially of a plurality of thin slabs that are movable relative to one another as disclosed in U.S. Pat. No. 5,997,247 and incorporated for reference. The thin slabs 10 are designed to be free to slide and spread out laterally across slot 8 to seal gap 6. However, this seal requires multiple thin slabs which can be an issue in ensuring the proper number of slabs have been installed in the slot. Too few slabs can result in an overly flexible seal that does not maintain an adequate seal and too many slabs can result in an overly stiff seal that does not move as necessary to maintain an adequate seal.
Therefore, in light of the requirements to provide a compliant seal to operate under high temperatures and mechanical loads, an improved seal is desired that overcomes the shortfalls of the prior art.